Corona: A Communication Service for Scalable, Reliable Group Collaboration Systems (Preliminary Design)

We consider the problem of providingcommunication protocol support for large-scale group collaboration systems for use in environments such as the Internet which are subject to packet loss, wide variations in end-to-end delays, and transient partitions. We identify a set of requirements that are critical for the design of such group collaboration systems. We present a communication service, Corona, that attempts to meet these requirements. Corona supports two communication paradigms: the publish/subscribe paradigm and the peer group paradigm. In the publish/subscribe paradigm one or more data sources or publishers send data to multiple subscribers. This paradigm is characterized by the anonymous nature of communication, where a publisher is aware of the set of subscribers, but the subscribers are unaware of each other and are only aware of the publisher that they are receiving data from. In the peer group paradigm of communication, on the other hand, all the group members are aware of each other, and can send and receive data directly to each other. We present the interfaces provided by Corona to group collaboration applications. We describe the semantics of each interface method call and show how they can meet a variety of group collaboration requirements. We describe the protocols used to implement these semantics.